Question

$5\times {10}^{19}$ electrons are flowing per sec through a heater and its resistance is $30\Omega$. What is the potential drop across it ?

• A. 110 V
• B. 220 V
• C. 240 V
• D. 260 V

Answer 1

The correct option is C 240 V

Charge on one electron is $1.6\times {10}^{-19}C$

So total charge on $5\times {10}^{19}$ electrons is $5\times {10}^{19}\times 1.6\times {10}^{-19}C=8C$

So $8C$ flows per second, so current is $8/1=8A$.

So voltage drop is $8A\times 30\Omega =240V$